var leftBtn = document.getElementById('leftBtn');
var rightBtn = document.getElementById('rightBtn');
var service_list = document.getElementById('service_list');

function next(){
    leftBtn.style.backgroundImage = "url('../../img/link-right.png')";
    leftBtn.style.transform = "rotateZ(180deg)";
    rightBtn.style.backgroundImage = "url('../../img/link-left.png')";
    rightBtn.style.transform = "rotateZ(180deg)";
    service_list.style.left = "-159px";
}
function last(){
    leftBtn.style.backgroundImage = "url('../../img/link-left.png')";
    leftBtn.style.transform = "";
    rightBtn.style.backgroundImage = "url('../../img/link-right.png')";
    rightBtn.style.transform = "";
    service_list.style.left = "0px";
}